INCOMPLETE ANTERIOR REGENERATION IN THE 



ABSENCE OF THE BRAIN IN LEP- 



TOPLANA LITTORALIS. 



LILIAN V. MORGAN. 



Previous experiments on the regeneration of planarians, more 

 particularly of marine forms, seem to indicate that the presence 

 of the cephalic ganglia is an important factor in regeneration. 

 The following experiments were carried out to test the question 

 further. The species used was a large marine planarian, Lcpto- 

 plana littoralis, very abundant at Pacific Grove, Cal., found under 

 wet stones just above the low-water mark. 



Lillie * and Morgan 2 have observed in Dciidroccchtm, that the 

 power of regeneration is limited in posterior pieces, the regen- 

 eration anteriorly never being complete if more than about the 

 anterior third of the worm is cut off. Schultz, 3 found in Lep- 

 toplana that anterior regeneration of a posterior piece cut at 

 any level posterior to the cephalic ganglia is very slow and 

 rarely if ever complete. Child 4 observed the same fact, and also 

 in the case of lateral regeneration that " when they [the cephalic 

 ganglia] are absent neither they nor the lateral part of the head 

 removed are regenerated, though lateral regeneration of other 

 parts may be more or less complete in the absence of the 

 ganglia." In L. littoralis there is also a very marked difference 

 in the rate and amount of regeneration of different kinds of pieces, 

 and also in the behavior of the pieces. 



Pieces of any size and shape, in which the cephalic ganglia 

 remained, responded quickly to stimuli that affect the normal 

 worm, and in general behaved like normal animals ; moreover 

 those that lived regenerated rapidly. Even small pieces (cut out 



1 Lillie, F. R., '01, "Notes on Regeneration and Regulation in Planarians," 

 Am. Joitrn. of Physiology, Vol. XL, p. 129. 



2 Morgan, T. H.,'o4, " Notes on Regeneration, "BlOL. BULLETIN, Vol. VI., p. 159. 



3 Schultz, E., '02, " Aus dem Gebiete der Regeneration, II., Ueber die Regen- 

 eration bei Turbellarien,'' Zeiffch. der u>iss. Zool., 72 Bd., p. i. 



4 Child, C. M.,'o4, " Studies on Regulation, IV., Some Experimental Modifica- 

 tions of Form-regulation in Leptoplana," Jonrn. of Exp. Zool., Vol. L, p. 95. 



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